Crane boom



Nov. 14, 1967 L. A, G. ALDEN 3,352,441

CRANE BOOM Filed Oct. 18, 1965 3 Sheets-Sheet l INVENTOR 44,95 A/VflfEjGUST/IF ALDEN ATTORNEYS Nov. 14, 1967 L.A. G. ALDEN CRANE BOOM FiledOct. 18, 1965 3 Sheets-Sheet 2 hill 1"" I FIGZ INVENTOR L421; AND/5,425"GUJ'MF ALDEN BY 5M ATTORNEYS Nov. 14, 1967 L A, G ALDEN 3,352,441 CRANEBOOM Filed Oct. 18, 1965 a Sheets-Sheet a 2 I 1 -1 l I I I I g JINVENTOR L425 4/1/5595 GUYMF ALDEN ATTORNEYS United States PatentOfifice 3,352,441 Patented Nov. 14, 1967 CRANE BOOM Lars Anders GustafAlden, Vaderbrunn, Nykoping, Sweden Filed Oct. 18, 1965, Ser. No.497,125 Claims priority, application Sweden, Oct. 28, 1964, 12,959/64 7Claims. (Cl. 214-130) This invention relates to a crane boom with an endportion that faces away from the fulcrum of the boom and is so arrangedas to permit extension thereof in relation to the remaining boom. Theprincipal characteristic of the invention is that the free end of thecrane boom is adapted at the pivotment of the boom to move in a pathuniform with another path constituted by a guide adjacent the fulcrum ofthe boom, by the actuation of two double-acting hydraulic operatingcylinders the working chambers of which communicate in pairs throughdirect conduits, one operating cylinder being interposed between thecrane boom and the guide while the other operating cylinder isinterposed between the crane boom and the extensible end portionthereof, the effective cross sectional area of the operating cylindercoacting with the guide being so much larger than that of the operatingcylinder coacting with the end portion as the distance of the free endof the crane boom from the fulcrum is greater than the distance of theguide from the fulcrum. Thus, the free end of the crane boom willautomatically move at the pivotment of the crane boom in a pathpredetermined by the guide, which involves great advantages in manydifferent respects.

These and further features of the invention will become apparent fromthe following description in which reference is made to the accompanyingdrawings diagrammatically illustrating an embodiment, chosen by Way ofexample, of the crane boom according to the invention.

In the drawings:

FIG. 1 is a side elevational view of the crane boom without any loadsupporting member;

FIG. 2 is a side elevation of the crane boom with a load receivingmember thereon;

FIG. 3 is a plan view of an additional assembly in a modified embodimentof the crane boom.

1 denotes the crane boom proper which is pivoted to a frame 2 about ahorizontal axis 3. At the end remote from the fulcrum 3 the boom 1 isprovided with an end portion 4 which is adapted for extensible movementlongitudinally of the boom and the free end 5 of which is the free endof the crane boom 1.

According to the invention, the free end 5 of the crane boom 1 isadapted at the pivotment of the boom automatically to move in a path 6indicated by broken lines in FIG. 1 and uniform with another pathconstituted by a guide 7 adjacent the fulcrum 3 of the boom 1. Thismovement is realized by means of two double-acting hydraulic operatingcylinders 8 and 9 the working chambers of which communicate in pairsthrough direct conduits 10 and 11. The operating cylinder 8 isinterposed between the boom 1 and the guide 7 while the operatingcylinder 9 is interposed between the crane boom 1 and the extensible endportion 4 thereof. To obtain the desired transmission ratio between thepistons in the operating cylinders 8 and 9 which are rigidly connectedwith the crane boom 1, the effective cross sectional area of theoperating cylinder 8 is so much greater than that of the operatingcylinder 9 as the distance of the free end 5 of the crane boom 1 fromthe fulcrum 3 is greater than the distance of the guide 7 from thefulcrum 3.

In the preferred embodiment illustrated, the operating cylinder 8 isarranged on one side and inside the guide 7 while the operating cylinder9 is arranged on the other side and outside said guide 7. For aneflicient utilization of the operating cylinders 8 and 9 their lengthsare inversely proportional to the effective cross sectional areasthereof so that the volumes are equal.

The piston rod of cylinder 8 can have its ends provided with a pair ofsmall wheels mounted on facing journals, and said wheels should engagein guide grooves provided in a rod 7 or like member. For this purposethe rod 7 may be of H-shaped cross-section.

The boom 1 is not telescopic but merely the end portion 4 is movablerelative to the boom 1 longitudinally thereof. The cylinder 9 is fixedlyconected with the boom 1 so that the end portion 4 will altogetherfollow the movements of the piston rod of said cylinder 9.

The cylinder 9 may be incorporated in the boom 1 as a fixed portionthereof. It can also have its rear end connected to the boom 1 at a pintransverse to the boom, which will be the normal mounting method. Alsothe cylinder 8 can be either a part fixedly connected to the boom 1 orhave its rear end pivoted to the boom 1 in which case the mountingnaturally is such as not to prevent in any way the movements of theextension 8'.

The end portion 4 is movably mounted at one side of the boom 1 so thatone side of the end portion is always accessible independently of theposition to which the end portion has been moved. It is on said sidethat the cylinder 14 is hinged to the pivot indicated in the drawing.

It should also be mentioned that the cylinder 8 is disposed on one sideof the boom 1, for which reason the extension 8' is outside the fulcrum3. Thus, the extension 8' can pass the fulcrum 3 unimpededly.

By providing the rod 7 on horizontal guides both at the upper and lowerends thereof there is formed a guide which is in the form of a plane.

In the embodiment shown in FIG. 1 the guide 7 is straight, but it couldvery Well be curved.

When the crane boom 1 for example is raised from the position shown byfull lines in FIG. 1 so that the distance from the fulcrum 3 to thepoint of engagement with the guide 7 increases, the piston in theoperating cylinder 8 will reduce the volume of the working chamberclosest to the guide 7, while the volume of the working chamber on theopposite side of the piston will increase. The fluid contained in thefirst-mentioned working chamber is there- 'by urged through the conduit10 into that Working chamber of the operating cylinder 9 which isclosest to the guide 7. The piston of the operating cylinder 9 is urgedtowards the the extensible end portion 4 which as a consequence will bepushed in an outward direction. The volume of that working chamber inthe operating cylinder 9 which is closest to the extensible end portion4 will thus decrease and the fluid contained in said working chamberwill be urged through the conduit 11 to that working chamber in theoperating cylinder 8 which is closest to the fulcrum 3.

By dimensioning and placing the operating cylinders 8 and 9 in themanner outlined hereinbefore the free end 5 will always be situated onthe line 6 parallel to the guide 7, as has been indicated by brokenlines. To realize this the piston in the operating cylinder 8 isequipped with an extension 8 which is similar to a piston rod andcompensates for the volume of the piston rod in the operating cylinder9. In another embodiment the pistons in the two operating cylinders 8and 9 may be equipped with extensions similar to piston rods and havingthe same cross sectional area as the piston rods proper.

The guide 7 need not necessarily be linear but may be a plane, providedthat the crane boom also is pivoted about a vertical axis 12intersecting the fulcrum 3. According to FIG. 3, said guide is planarbut it may also be curved, preferably having a single curvature in themanner of a cylindrical circumferential surface.

In FIG. 2 the loading gear illustrated in FIG. 1 has been provided witha load supporting member 13, for instance a platform, adapted to bemoved vertically along a house wall or the like. The member 13 ispivoted at 5 to the extensible end portion of the crane boom. 7

A hydraulic operating cylinder 14 is hinged between the load supportingmember 13 and the end portion 4 while another hydraulic operatingcylinder is hinged between the crane boom 1 and the frame 2. The hingepoints of the operating cylinder 14 at the load supporting member 13 andthe end portion 4 are so placed as to form together with the pivot point5 of the load supporting member the corners of a triangle similar to orcongruent with the triangle the corners of which are formed by the hingepoints of the operating cylinder 15 at the crane boom 1 and the frame 2as well as the fulcrum 3 of the crane boom 1 at the frame 2.

The operating cylinders 14 and 15 are double-acting and designed withworking chambers so communicating in pairs through direct conduits 16and 17 as to ensure that the load supporting member 13 always occupiesthe same angular position in relation to the ground irrespective of thepivotment of the crane boom 1 in the vertical plane. A horizontalplatform can thus always be kept horizontal in the manner described.

FIG. 3 shows an additional assembly for the crane boom according toFIGS. 1 and 2 when the guide 7 is not linear but a plane. The saidassembly which comprises a pair of double-acting hydraulic operatingcylinders 18 and 19 with working chambers communicating in pairs throughdirect conduits 20 and 21, ensures that the load supporting member 13always retains its orientation in space. For the operating cylinderunits 18, 19 are of the same nature as the operating cylinder units 14,15. The crane boom 1 according to the invention thus permits moving ahorizontal platform in parallel with a house wall, which in turn isplane parallel with the guide plane 7.

While the invention has been described in the aforementioned embodimentswith reference to the accompanying drawings it is readily understood bythose skilled in the art that it permits of modification within thescope of the appended claims.

What I claim and desire to secure by Letters Patent is:

1. A crane boom comprising a fulcrum, a guide located adjacent saidfulcrum of said boom, a free end portion extending away from the fulcrumof said boom and extensible in relation to the remaining portion of saidboom, said free end portion being adapted at the pivoting of said boomto move in a path uniform with another path formed by said guide, twodouble-acting hydraulic operating cylinders having working chamberscommunicating in pairs through direct conduits, one operating cylinderbeing interposed between said boom and said guide While the otheroperating cylinder is interposed between said boom and said extensiblefree end portion, the effective cross sectional area of the operatingcylinder coacting with said guide being so much larger than that of theoperating cylinder coacting with said free end portion as the distanceof said free end portion from said fulcrum is greater than the distanceof said guide from said fulcrum.

2. A crane boom in accordance with claim 1, wherein said guide islinear.

3. A crane boom in accordance with claim 2, wherein said guide isstraight.

4. A crane boom according to claim 1, wherein said guide is a plane.

5. A crane boom according to claim 1, wherein said operating cylinderinterposed between said boom and said guide is arranged inside and onone side of said guide while said operating cylinder interposed betweensaid boom and said free end portion is arranged on the other side andoutside said guide.

6. A crane boom in accordance with claim 1, wherein the lengths of saidoperating cylinders are inversely proportional to their effective crosssectional areas.

7. A crane boom in accordance with claim 1, wherein said boom isprovided at said free end portion with a platform load supporting memberpivoted to said boom and having two double-acting hydraulic operating.cylinders with working chambers comunicating in pairs through directconduits cooperating with said member to retain its orientation in spaceirrespective of the pivoting of said boom.

References Cited UNITED STATES PATENTS 2,731,162 l/1956 Walstrom 214-2,786,723 3/1957 Harsch 214 2,860,793 11/1953 Lapsley 214-140 2,990,0726/1961 Mindrum 214-140 3,187,911 6/1965 Christensen 214-140 SCHULZ,Primary Examiner.

1. A CRANE BOOM COMPRISING A FULCRUM, A GUIDE LOCATED ADJACENT SAIDFULCRUM OF SAID BOOM, A FREE END PORTION EXTENDING AWAY FROM THE FULCRUMOF SAID BOOM AND EXTENSIBLE IN RELATION TO THE REMAINING PORTION OF SAIDBOOM, SAID FREE END PORTION BEING ADAPTED AT THE PIVOTING OF SAID BOOMTO MOVE IN PATH UNIFORM WITH ANOTHER PATH FORMED BY SAID GUIDE, TWODOUBLE-ACTING HYDRAULIC OPERATING CYLINDERS HAVING WORKING CHAMBERSCOMMUNICATING IN PAIRS THROUGH DIRECT CONDUITS, ONE OPERATING CYLINDERBEING INTERPOSED BETWEEN SAID BOOM AND SAID GUIDE WHILE THE OTHEROPERATING CYLINDER IS INTERPOSED BETWEEN SAID BOOM AND SAID EXTENSIBLEFREE END PORTION, THE EFFECTIVE CROSS SECTIONAL AREA OF THE OPERATINGCYLINDER COACTING WITH SAID